Magnetic tunnel junction structure

ABSTRACT

A magnetic tunnel junction (MTJ) device is formed by a process that includes forming a trench in a substrate and depositing an MTJ structure within the trench. The MTJ structure includes a bottom electrode, a fixed layer, a tunnel barrier layer, a free layer, and a top electrode. The process includes applying reverse photo etching to remove material that is not directly over the trench. The process also includes plagiarizing the MTJ structure without performing a photo-etch process on the MTJ structure.

I. CLAIM OF PRIORITY

The present application claims priority from and is a divisional ofpending U.S. patent application Ser. No. 12/546,610, filed Aug. 24,2009, which claims priority to U.S. patent application Ser. No.12/041,957 filed Mar. 4, 2008, now issued as U.S. Pat. No. 7,579,197,both of which are incorporated herein by reference in their entireties.

II. FIELD

The present disclosure is generally related to a magnetic tunneljunction (MTJ) structure.

III. DESCRIPTION OF RELATED ART

In general, widespread adoption of portable computing devices andwireless communication devices has increased demand for high-density andlow-power non-volatile memory. As process technologies have improved, ithas become possible to fabricate magneto-resistive random access memory(MRAM) based on magnetic tunnel junction (MTJ) devices. Traditional spintorque tunnel (STT) junction devices are typically formed as flat stackstructures. Such devices typically have two-dimensional magnetic tunneljunction (MTJ) cells with a single magnetic domain. An MTJ celltypically includes a bottom electrode, an anti-ferromagnetic layer, afixed layer (i.e., a reference layer formed from a ferromagneticmaterial that carries a magnetic field having a fixed or pinnedorientation by an anti-ferromagnetic (AF) layer), a tunnel barrier layer(i.e., a tunneling oxide layer), a free layer (i.e., a secondferromagnetic layer that carries a magnetic field having a changeableorientation), and a top electrode. The MTJ cell represents a bit valueby a magnetic field induced in the free layer. A direction of themagnetic field of the free layer relative to a direction of a fixedmagnetic field carried by the fixed layer determines the bit value.

Typically, the magnetic tunnel junction (MTJ) cell is formed bydepositing multiple layers of material, by defining a pattern onto thelayers, and by selectively removing portions of the layers according tothe pattern. Conventional MTJ cells are formed to maintain an aspectratio of length (a) to width (b) that is greater than one in order tomaintain a magnetic isotropic alignment. Conventionally, the aspectratio of the MTJ cells is maintained by controlling an accuracy of theMTJ pattern and by performing an MTJ photo and etch process. In aparticular instance, a hard mask may be used to transfer and define theMTJ pattern accurately. Unfortunately, the MTJ stack may includemagnetic films that are basically metal films and that have a relativelyslow etch rate, so the hard mask may need to be relatively thick. Foradvance pattern critical dimension (CD) control, advanced patterningfilm (APF) and bottom anti-reflection coating (BARC) layers are includedin the MTJ photo and etch process. However, while these additionallayers increase process complexity (both in terms of additionaldeposition processes and in terms of additional layer photo/etch andclean processes), the MTJ cell structure may experience erosion, whichmay result in an undesired slope, corner rounding, and undesired filmloss. Such damage can impact a contact resistance of the MTJ structureand potentially even expose or damage the MTJ junction.

IV. SUMMARY

In a particular illustrative embodiment, a magnetic tunnel junction(MTJ) device formed by a process is disclosed. The process includesforming a trench in a substrate. The process further includes depositingan MTJ structure within the trench. The MTJ structure includes a bottomelectrode, a fixed layer, a tunnel barrier layer, a free layer, and atopelectrode. The process includes applying reverse photo etching processto remove material that is not directly over the trench. The processalso includes planarizing the MTJ structure without performing aphoto-etch process on the MTJ structure.

in another particular embodiment, a magnetic tunnel junction (MTJ)structure is disclosed that includes a bottom electrode, a fixed layer,a tunnel barrier layer, a free layer, and atop electrode. The bottomelectrode is coupled to a bottom surface of the fixed layer and extendsalong at least one sidewall of the fixed layer.

One particular advantage provided by embodiments of the disclosedmethods of forming a magnetic tunnel junction (MTJ) structure is thatoxidation, erosion and corner rounding can be reduced by using a trenchto define dimensions of the MTJ structure without photo/etching the MTJstructure. In general, the trench is formed in an oxide base substrate,which is easier to photo-etch than the MTJ metal films. Further, it iseasier to precisely photo-etch the oxide base substrate than the metallayers. Instead, a reverse trench photo-etch process and aChemical-Mechanical Planarization (CMP) process can be used to removeexcess material, without introducing erosion, corner rounding or otherissues that may impact performance of the MTJ structure.

Another particular advantage is provided in hat a process window forformation of MTJ structures is improved, i.e., enlarged, and the overallreliability of MTJ process and resulting MTJ structure is also improved.

Other aspects, advantages, and features of the present disclosure willbecome apparent after review of the entire application, including thefollowing sections: Brief Description of the Drawings, DetailedDescription, and the Claims.

V. BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of a representative: example of a magnetic tunneljunction (MTJ) cell;

FIG. 2 is a block diagram of a circuit device including a representativeembodiment of a magnetic tunnel junction (MTJ) cell including a topelectrode, an MTJ stack, and a bottom electrode;

FIG. 3 is a top view of a particular illustrative embodiment of acircuit device including a magnetic tunnel junction (MTJ) cell having asubstantially rectangular shape;

FIG. 4 is a cross-sectional view of the circuit device of FIG. 3 takenalong line 4-4 in FIG. 3;

FIG. 5 is a top view of a second particular illustrative embodiment of acircuit device including a magnetic tunnel junction (MTJ) cell having asubstantially elliptical shape;

FIG. 6 is a top view of a third particular illustrative embodiment of acircuit device including a magnetic tunnel junction (MTJ) cell;

FIG. 7 is a cross-sectional view of the circuit device of FIG. 6 takenalong line 7-7 in FIG. 6;

FIG. 8 is a top view of a particular illustrative embodiment of a memorydevice including a substrate having a magnetic tunnel junction cell thatis adapted to store multiple bits;

FIG. 9 is a cross-sectional diagram of the circuit device of FIG. 8taken along line 9-9 in FIG. 8;

FIG. 10 is a cross-sectional diagram of the circuit device of FIG. 8taken along line 10-10 in FIG. 8;

FIG. 11 is a top view of another particular illustrative embodiment of amemory device including a substrate having a magnetic tunnel junctioncell that is adapted to store multiple bits;

FIG. 12 is a cross-sectional diagram of the circuit device of FIG. 11taken along line 12-12 in FIG. 11;

FIG. 13 is a cross-sectional diagram of the circuit device of FIG. 11taken along line 13-13 in FIG. 11;

FIG. 14 is a cross-sectional view of circuit substrate after depositionof a cap film layer and after via photo/etching, photo-resist strip, viafill, and via Chemical-Mechanical Planarization (CMP) processes;

FIG. 15 is a cross-sectional view of the circuit substrate of FIG. 14after inter-layer dielectric layer deposition, cap film deposition,trench photo/etch process, bottom electrode deposit, magnetic tunneljunction (MTJ) films deposition, top electrode deposit, and reversephoto/etch processing;

FIG. 16 is a cross-sectional view of the circuit substrate of FIG. 15after reverse photo-resist strip and MTJ CMP processing to stop at thecap film layer;

FIG. 17 is a cross-sectional view of the circuit substrate of FIG. 16taken along line 17-17 in FIG. 16 after spinning on photo resist andafter photo-etching to remove a sidewall of the MTJ stack providing aprocess opening;

FIG. 18 is a cross-sectional view of the circuit substrate of FIG. 17after filling the process opening with IDL material and oxide and a CMPprocess stop at the cap layer;

FIG. 19 is a cross-sectional view of the circuit substrate of FIG. 18taken along the line 19-19 in FIG. 18 after deposition of a first IDLlayer, via processing, and metal film deposition and patterning of a topwire trace;

FIGS. 20-21 illustrate a flow diagram of a particular illustrativeembodiment of a method of forming a magnetic tunnel junction (MTJ) cell;

FIG. 22 is a flow diagram of a second particular illustrative embodimentof a method of forming an MTJ cell;

FIG. 23 is a flow diagram of a third particular illustrative embodimentof a method of forming an MTJ cell;

FIG. 24 is a flow diagram of a fourth particular illustrative embodimentof a method of forming an NIT.1 cell; and

FIG. 25 is a block diagram of a representative wireless communicationsdevice including a memory device having a plurality of MTJ cells.

VI. DETAILED DESCRIPTION

FIG. 1 is a cross-sectional view of a particular embodiment of a portionof a magnetic tunnel junction (MTJ) cell 100, which may be formedaccording to the methods and embodiments described with respect to FIGS.3-24. The MTJ cell 100 includes an MTJ stack 102 having a free layer104, a tunnel barrier layer 106, a fixed (pinned) layer 108, and ananti-ferromagnetic (AF) layer 126. The MTJ stack 102 is coupled to a bitline 110. Further, the MTJ stack 102 is coupled to a source line 114 viaa bottom electrode 116 and a switch 118. A word line 112 is coupled to acontrol terminal of the switch 118 to selectively activate the switch118 to allow a write current 124 to flow from the bit line 110 to thesource line 114. In the embodiment shown, the fixed layer 108 includes amagnetic domain 122 that has a fixed orientation. The free layer 104includes a magnetic domain 120, which is programmable via the writecurrent 124. As shown, the write current 124 is adapted to program theorientation of the magnetic domain 120 at the free layer 104 to a zerostate (i.e., the magnetic domains 120 and 122 are oriented in the samedirection). To write a one value to the MTJ cell 100, the write current124 is reversed, causing the orientation of the magnetic domain 120 atthe free layer 104 to flip directions, such that the magnetic domain 120extends in a direction opposite to that of the magnetic domain 122.

FIG. 2 is a cross-sectional view of another particular embodiment of anMTJ cell 200, which includes a synthetic fixed layers structure andwhich may be formed according to the methods and embodiments describedwith respect to FIGS. 3-24. In particular, the MTJ cell 200 includes anMTJ stack 202 including the free layer 204, the tunnel barrier layer206, and the fixed layer 208. The free layer 204 of the MTJ stack iscoupled to the top electrode 210 via a buffer layer 230. In thisexample, the fixed layer 208 of the stack 202 is coupled to the bottomelectrode 216 via an anti-ferromagnetic layer 238. Additionally, thefixed layer 208 includes a first pinned (fixed) layer 236, a bufferlayer 234, and a second pinned (fixed) layer 232. The first and secondpinned layers 236 and 232 have respective magnetic domains which areoriented in opposing directions in a synthetic fixed layer structure,thereby increasing an overall resistance and balancing magnetic strayfield of the MTJ stack 202. In a particular embodiment, such stray fieldreduction can balance a magnetic field of the MTJ stack 202. In otherembodiments, additional layers may be included, such as one or more seedlayers; buffer layers; stray field balance layers; connection layers;performance enhancement layers, such as synthetic fixed layers,synthetic free (SyF) layers, or dual spin filter (DSF); or anycombination thereof.

FIG. 3 is a top view of a particular illustrative embodiment of acircuit device 300 including a magnetic tunnel junction (MU) cell 304having a substantially rectangular shape. The circuit device 300includes a substrate 302 that has the MTJ cell 304. The MTJ cell 304includes a bottom electrode 306, an Mil stack 308, a center electrode310, and a via 312. The MTJ cell 304 has a first sidewall 314, a secondsidewall 316, a third sidewall 318, and a fourth sidewall 320. Thesecond sidewall 316 includes a second magnetic domain 322 to represent afirst data value and the fourth sidewall 320 includes a fourth magneticdomain 324 to represent a second data value. A bottom wall (not shown)may include a bottom magnetic domain 446 (see FIG. 4) to representanother data value. The first and third sidewalls 314 and 318 may alsocarry magnetic domains, depending on a particular implementation.

The MTJ cell 304 has a length (a) and a width (b). The length (a)corresponds to the length of the second and fourth sidewalls 316 and320. The width (b) corresponds to the length of the first and thirdsidewalls 314 and 318. In this particular example, the length (a) of theMTJ cell 304 is greater than the width (b).

FIG. 4 is a cross-sectional view 400 of the circuit device 300 of FIG. 3taken along line 4-4 in FIG. 3. The view 400 includes the substrate 302shown in cross-section including the MTJ cell 304, the via 312, the topelectrode 310, the MTJ stack 308, and the bottom electrode 306. Thesubstrate 302 includes a first inter-layer dielectric layer 432, a firstcap layer 434, a second inter-layer dielectric layer 436, a second caplayer 438, a third cap layer 440, and a third inter-layer dielectriclayer 442.

A trench is formed in the second cap layer 438 and the secondinter-layer dielectric layer 436 to receive the bottom electrode 306,the MTJ stack 308, and the top electrode 310. The trench has a trenchdepth (d) and the MTJ stack 308 has a depth (c) that is approximatelyequal to the trench depth (d) minus a thickness of the bottom electrode306. A bottom via 444 extends through the first cap layer 434 and thefirst inter-layer dielectric layer 432 and is coupled to the bottomelectrode 306. The via 312 extends from a surface 430 of the substrate302 through the third inter-layer dielectric layer 442 and the third caplayer 440 and is coupled to the top electrode 310. The surface 430 maybe a substantially planar surface.

FIG. 5 is a top view of a second particular illustrative embodiment of acircuit device 500 including a magnetic tunnel junction (MTJ) cell 504having a substantially elliptical shape. The circuit device 500 includesa substrate 502 having the MTJ cell 504. The. MTJ cell 504 includes abottom electrode 506, an MTJ stack 508, a top electrode 510, and a via512 that extends from a surface (such as the surface 430 illustrated inFIG. 4) to the top electrode 510. The MTJ cell 504 includes a firstsidewall 516 and a second sidewall 518, which are adapted to carryindependent magnetic domains 522 and 524, respectively. A respectiveorientation of each of the independent magnetic domains 522 and 524 mayrepresent a respective data value. In addition, the MTJ cell 504 mayinclude a bottom wall adapted to carry another independent magneticdomain, such as the bottom domain 446 of FIG. 4, which may representanother data value.

The MTJ cell 504 includes a length (a) and a width (1) where the length(a) is greater than the width (b). In a particular embodiment, thecross-sectional view of FIG. 4 may also represent a cross-section takenalong lines 4-4 in FIG. 5. In this example, the MTJ cell 504 may beformed within a trench having a depth (d) such that the MTJ cell 504 hasa depth (c), as illustrated in FIG. 4. In this particular example, theMTJ cell 504 may be formed such that the length (a) is greater than thewidth (h) and the width (b) is much greater than the trench depth (d) orthe MTJ cell depth (c). Alternatively, the MTJ cell 504 may be formedsuch that the MTJ cell 504 has a trench depth (d) that is greater thanthe MTJ cell depth (c), which in turn is greater than the length (a), asillustrated in FIGS. 6 and 7.

FIG. 6 is a top view of a third particular illustrative embodiment of acircuit device 600 including a magnetic tunnel junction (MTJ) cell 604.The circuit device 600 includes a substrate 602 that has the MTJ cell604. The MTJ cell 604 includes a bottom electrode 606, an MTJ stack 608,a center electrode 610 and a via 612. The MTJ cell 604 has a firstsidewall 614, a second sidewall 616, a third sidewall 618, and a fourthsidewall 620. The second sidewall 616 includes a second magnetic domain622 adapted to represent a first data value and the fourth sidewall 620includes a fourth magnetic domain 624 adapted to represent a second datavalue. A bottom wall 770 may include a bottom magnetic domain 772, asdepicted in FIG. 7. The first and third sidewalls 614 and 618 may alsocarry magnetic domains, depending on the particular implementation.

The MTJ cell 604 has a length (a) and a width (b). The length (a)corresponds to the length of the second and fourth sidewalls 616 and620. The width (b) corresponds to the length of the first and thirdsidewalls 614 and 618. In this particular example, the length (a) of theMTJ cell 604 is greater than the width (b).

FIG. 7 is a cross-sectional view of the circuit device of FIG. 6 takenalong line 7-7 ire FIG. 6. The view 700 includes the substrate 602 shownin cross-section including the MTJ cell 604, the via 612, the topelectrode 610, the MTJ stack 608, and the bottom electrode 606. Thesubstrate 602 includes a first inter-layer dielectric layer 732, a firstcap layer 734, a second inter-layer dielectric layer 736, a second caplayer 738 a third cap layer 740 and a third inter-layer dielectric layer742.

A trench is formed in the second cap layer 738 and the secondinter-layer dielectric layer 736 to receive the bottom electrode 606,the MTJ stack 608, and the top electrode 610. The trench has a trenchdepth (d) and the MTJ stack 608 has a depth (c) that is approximatelyequal to the trench depth (d) minus a thickness of the bottom electrode606. A bottom via 744 extends from a bottom surface 790 through thefirst cap layer 734 and the first inter-layer dielectric layer 732 andis coupled to the bottom electrode 606. The via 612 extends from a topsurface 780 of the substrate 602 through the third inter-layerdielectric layer 742 and the third cap layer 740 and is coupled to thetop electrode 610. The top surface 780 may be a substantially planarsurface.

In a particular embodiment, the trench depth (d) is greater than the MTJcell depth (c), which are both greater than the length (a) of the MTJcell 604. In this particular example, the magnetic domains 622 and 624are oriented vertically (i.e., in a direction of the depth (d) of thesidewalk, as opposed to horizontally in a direction of the length (a) ofthe sidewalls).

FIG. 8 is a top view of a particular illustrative embodiment of a memorydevice 800 including a substrate 802 with having a magnetic tunneljunction (MTJ) cell 804 that is adapted to store multiple data bits. Themagnetic tunnel junction (MTJ) cell 804 includes a bottom electrode 806,an MTJ stack 808, and a center electrode 810. The MTJ cell 804 has alength (a) and a width (b), where the length (a) is greater than thewidth (b). The substrate 802 includes a top via 836 that is coupled tothe center electrode 810 and includes a bottom via 832 that is coupledto the bottom electrode 806. The substrate 802 also includes a firstwire trace 834 that is coupled to the top via 836 and a second wiretrace 830 that is coupled to the bottom via 832. The substrate 802includes a process opening 838.

The MTJ stack 808 includes a fixed (pinned) magnetic layer that carriesa fixed magnetic domain having a fixed orientation, a tunnel barrierlayer, and a free magnetic layer having a magnetic domain that can bechanged or programmed via a write current. The MTJ stack 808 may alsoinclude an anti-ferromagnetic layer to pin the fixed magnetic layer. Ina particular embodiment, the fixed magnetic layer of the MTJ stack 808may include one or more layers. Additionally, the MTJ stack 808 mayinclude other layers. The MTJ cell 804 includes a first sidewall 812 tocarry a first magnetic domain 822, a second sidewall 814 to carry asecond magnetic domain 824, and a third sidewall 816 to carry a thirdmagnetic domain $26. The MTJ cell 804 also includes bottom wall 970 tocarry fourth magnetic domain 972 (see FIG. 9). The first, second, third,and fourth magnetic domains 822, 824, 826, and 972 are independent. In aparticular embodiment, the first, second, third, and fourth magneticdomains 822, 824, 826, and 972 are configured to represent respectivedata values. In general, the orientations of the magnetic domains 822,824, 826, and 972 are determined by the stored data value. For example,a “0” value is represented by a first orientation while a “1” value isrepresented by a second orientation.

FIG. 9 is a cross-sectional diagram 900 of the circuit device 800 ofFIG. $ taken along line 9-9 in FIG. 8. The diagram 900 includes thesubstrate 802 having a first inter-layer dielectric layer 950, a secondinter-layer dielectric layer 952, a first cap layer 954, a thirdinter-layer dielectric layer 956, a second cap layer 958, a third caplayer 960, a fourth inter-layer dielectric layer 962, and a fifthinter-layer dielectric layer 964. The substrate 802 has a first surface980 and a second surface 990. The substrate 802 also includes the MTJstructure 804 including the MTJ stack 808. The bottom electrode 806, theMTJ stack 808, and the top electrode 810 are disposed within a trench inthe substrate 802. The trench has a depth (d).

The substrate 802 includes the second wire trace 830 disposed at thesecond surface 990. The second wire trace 830 is coupled to the bottomvia 832, which extends from the second wire trace 830 to a portion ofthe bottom electrode 806. The substrate 802 also includes the first wiretrace 834 disposed at the first surface 980. The first wire trace 834 iscoupled to the top via 836, which extends from the first wire trace 834to the center electrode 810. The center electrode 810 is coupled to theMTJ stack 808. The substrate 802 also includes the process opening 838,which may be formed by selectively removing a portion of the MTJstructure 804 and depositing an inter-layer dielectric material withinthe processing opening 838, followed by an oxide CMP.

In a particular embodiment, the MTJ stack 808 includes the secondsidewall 814, which carries the second magnetic domain 824. The secondmagnetic domain 824 is adapted to represent a second data value. The MTJstack 808 also includes a bottom wall 970 having a bottom magneticdomain 972, which is adapted to represent a fourth data value. In aparticular example, a data value can be read from the MTJ stack 808 byapplying a voltage to the first wire trace 834 and by comparing acurrent at the second wire trace 830 to a reference current.Alternatively, a data value may be written to the MTJ stack 808 byapplying a write current to one of the first and second wire traces 834and 830. In a particular embodiment, the length (a) and the width (b) ofthe MTJ stack 808 illustrated in FIG. 8 are greater than the trenchdepth (d), and the magnetic domain 824 carried by the second sidewall814 extends in a direction that is substantially parallel to the firstsurface 980 of the substrate 802 and in a direction of the width (b)illustrated in FIG. 8. In this particular view, the magnetic domain 824extends in a direction that is normal to the page view of FIG. 9(outward from the page as indicated by an arrow head (“”) or into thepage as indicated by a tail of an arrow (“*”)).

FIG. 10 is a cross-sectional diagram 1000 of the circuit device 800 ofFIG. 8 taken along line 10-10 in FIG. 8. The diagram 1000 includes thesubstrate 802 having a first inter-layer dielectric layer 950, a secondinter-layer dielectric layer 952, a first cap layer 954, a thirdinter-layer dielectric layer 956, a second cap layer 958, a third caplayer 960, a fourth inter-layer dielectric layer 962, and a fifthinter-layer dielectric layer 964. The substrate 802 has a first surface980 and a second surface 990. The substrate 802 includes the MTJstructure 804 having the bottom electrode 806, the MTJ stack 808, andthe center electrode 810. The substrate 802 includes the first wiretrace 834 disposed and patterned at the first surface 980. The firstwire trace 834 is coupled to the top via 836, which extends from thefirst wire trace 834 to the center electrode 810. The substrate 802 alsoincludes the second wire trace 830 at the second surface 990. The secondwire trace 830 is coupled to the bottom via 832, which extends from thesecond wire trace 830 to a portion of the bottom electrode 806. The MTJstack 808 includes the first sidewall 816 to carry the first magneticdomain 826, the third sidewall 812 to carry the third magnetic domain822, and the bottom wall 970 to carry the bottom magnetic domain 972. Inthis particular view, the magnetic domains 826, 822, and 972 extend in adirection that is normal to the page view of FIG. 10 (outward from thepage as indicated by an arrow head (“”) or in o the page as indicatedby a tail of an arrow (“*”)).

In a particular embodiment, the MTJ stack 808 is adapted to store up tofour unique data values. A first data value may be represented by thefirst magnetic domain 822, a second data value may be represented by thesecond magnetic domain 824, a third data value may be represented by thethird magnetic domain 826, and a fourth data value may be represented bythe bottom magnetic domain 972. In another particular embodiment, afourth sidewall may be included to carry a fourth magnetic domain, whichmay represent a fifth data value.

FIG. 11 is a top view of a particular illustrative embodiment of amemory device 1100 including a substrate 1102 with a magnetic tunneljunction (MTJ) cell 1104 in a deep trench that is adapted to storemultiple data values, such as multiple bits. The magnetic tunneljunction (MTJ) cell 1104 includes a bottom electrode 1106, an MTJ stack1108, and a center electrode 1110. The MTJ cell 1104 has a length (a)and a width (b), where the length (a) is greater than the width (b). Thesubstrate 1102 includes atop via 1136 that is coupled to the centerelectrode 1110 and includes a bottom via 1132 that is coupled to thebottom electrode 1106. The substrate 1102 also includes a first wiretrace 1134 that is coupled to the bottom via 1132 and a second wiretrace 1130 that is coupled to the top via 1136. The substrate 1102includes a process opening 1138.

The MTJ stack 1108 includes a fixed (pinned) magnetic layer that may bepinned by an anti-ferromagnetic layer and that carries a fixed magneticdomain having a fixed orientation, a tunnel barrier layer, and a freemagnetic layer having a magnetic domain that can be changed orprogrammed via a write current. In a particular embodiment, the fixedmagnetic layer of the MTJ stack 1108 may include one or more layers.Additionally, the MTJ stack 1108 may include other layers. The MTJ cell1104 includes a first sidewall 1112 to carry a first magnetic domain1122, a second sidewall 1114 to carry a second magnetic domain 1124, anda third sidewall 1116 to carry a third magnetic 1126. The MU cell 1104may also include a bottom wall 1270 to carry a fourth magnetic domain1272 (see FIG. 12). The first, second, third, and fourth magneticdomains 1122, 1124, 1126, and 1272 are independent. In a particularembodiment, the first, second, third, and fourth magnetic domains 1122,1124, 1126, and 1272 are configured to represent respective data values.In general, the orientations of the magnetic domains 1122, 1124, 1126,and 1272 are determined by the stored data value. For example, a “0”value is represented by a first orientation while a “1” value isrepresented by a second orientation.

FIG. 12 is a cross-section 1 diagram 1200 of the circuit device 1100 ofFIG. 11 taken along line 12-12 in FIG. 11. The diagram 1200 includes thesubstrate 1102 having a first inter-layer dielectric layer 1250, asecond inter-layer dielectric layer 1252, a first cap layer 1254, athird inter-layer dielectric layer 1256, a second cap layer 1258, athird cap layer 1260, a fourth inter-layer dielectric layer 1262, and afifth inter-layer dielectric layer 1264. The substrate 1102 has a firstsurface 1280 and a second surface 1290. The substrate 1102 also includesthe MTJ structure 1104 including the MTJ stack 1108. The bottomelectrode 1106, the MTJ stack 1108, and the top electrode 1110 aredisposed within a trench in the substrate 1102. The trench has a depth(d). In this instance, the depth (d) is greater than the width (b) ofthe sidewall 1114.

The substrate 1102 includes the second wire trace 1130 disposed andpatterned at the first surface 1280. The second wire trace 1130 iscoupled to the top via 1136, which extends from the second wire trace1130 to the center electrode 1110. The center electrode 1110 is coupledto the MTJ stack 1108. The substrate 1102 also includes the first wiretrace 1134 disposed at the second surface 1290. The first wire trace1134 is coupled to the bottom via 1132, which extends from the firstwire trace 1134 to a portion of the bottom electrode 1106. The substrate1102 further includes the process opening 1138, which may be formed byselectively removing a portion of the MTJ stack 1108 and by depositingan inter-layer dielectric material within the processing opening 1138,followed by an oxide CMP process.

In a particular embodiment, the MTJ stack 1108 includes the secondsidewall 1114, which carries the second magnetic domain 1124. The secondmagnetic domain 1124 is adapted to represent a second data value. TheMTJ stack 1108 also includes a bottom wall 1270 having a bottom magneticdomain 1272, which is adapted to represent a fourth data value. In aparticular example, a data value can be read from the MTJ stack 1108 byapplying a voltage to the second wire trace 1130 and by comparing acurrent at the first wire trace 1134 to a reference current.Alternatively, a data value may be written to the MTJ stack 1108 byapplying a write current between the first and second wire traces 1134and 1130. In a particular embodiment, the length (a) and the width (b)of the MTJ stack 1108 illustrated in FIG. 11 are less than the trenchdepth (d), and the magnetic domain 1124 carried by the second sidewall1114 extends in a direction that is substantially perpendicular to thefirst surface 1280 of the substrate 1102 and in a direction of the depth(d).

FIG. 13 is a cross-sectional diagram 1300 of the circuit device 1100 ofFIG. 11 taken along line 13-13 in FIG. 11. The diagram 1300 includes thesubstrate 1102 having a first inter-layer dielectric layer 1250, asecond inter-layer dielectric layer 1252, a first cap layer 1254, athird inter-layer dielectric layer 1256, a second cap layer 1258, athird cap layer 1260, a fourth inter-layer dielectric layer 1262, and afifth inter-layer dielectric layer 1264. The substrate 1102 has a firstsurface 1280 and a second surface 1290. The substrate 1102 includes theMTJ structure 1104 having the bottom electrode 1106, the MTJ stack 1108,and the center electrode 1110. The substrate 1102 includes the firstwire trace 1134 disposed and patterned at the second surface 1290. Thefirst wire trace 1134 is coupled to the bottom via 1132, which extendsfrom the first wire trace 1134 to a portion of the bottom electrode1106. The substrate 1102 also includes the second wire trace 1130 at thefirst surface 1280. The second wire trace 1130 is coupled to the top via1136, which extends from the second wire trace 1130 to the centerelectrode 1110.

The MTJ stack 1108 includes the first sidewall 1116 to carry the firstmagnetic domain 1126, the third sidewall 1112 to carry the thirdmagnetic domain 1122, and the bottom wall 1270 to carry the bottommagnetic domain 1272. In this particular view, the trench depth (d) isgreater than the length (a) and the width (b) of the MTJ stack 1108, andthe first and third magnetic domains 1122 and 1126 extend in a directionthat is substantially perpendicular to the first surface 1280. Thelength (a) is greater than the width (b) of the MTJ stack 1108, and thefourth magnetic domain 1172 extends in a direction that is substantiallynormal to the page view (outward from the page as indicated by an arrowhead (“”) or into the page as indicated by a tail of an arrow (“*”)).

In a particular embodiment, the MTJ stack 1108 is adapted to store up tofour unique data values. A first data value may be represented by thefirst magnetic domain 1122, a second data value may be represented bythe second magnetic domain 1124, a third data value may be representedby the third magnetic domain 1126, and a fourth data value may berepresented by the bottom magnetic domain 1272. In another particularembodiment, a fourth sidewall may be included to carry a fourth magneticdomain, which may represent a fifth data value.

FIG. 14 is a cross-sectional view of a circuit substrate 1400 afterdeposition of a cap film layer and after via photo-etching, photo-resiststrip, via fill, and via Chemical-Mechanical Planarization (CMP)processes. The circuit substrate 1400 includes a first inter-layerdielectric layer 1401, and a wire trace 1403, a second inter-layerdielectric layer 1402 disposed on top of the first inter-layerdielectric layer 1401, and a cap film layer 1404 disposed on top of theinter-layer dielectric layer 1402. In a particular embodiment, aphoto-resistive layer was applied by spinning photo-resist onto the capfilm layer 1404. A photo-etching process was applied to define a patternin the cap layer 1404 and the inter-layer dielectric 1402 by thephoto-resistive layer. The photo-resistive layer was stripped afteretching to expose an opening or via 1406 through the cap film layer 1404and the inter-layer dielectric layer 1402. A conductive material or viafill material 1408 was deposited into the opening 1406, and a via. CMPprocess was performed to planarize the circuit substrate 1400.

FIG. 15 is a cross-sectional view 1500 of the circuit substrate 1400 ofFIG. 14 after inter-layer dielectric layer deposition, cap filmdeposition, trench photo-etch process, trench photo resist strip, bottomelectrode deposit, magnetic tunnel junction (MTJ) films deposit, topelectrode deposit, and reverse photo-etch processing. The circuitsubstrate 1400 includes the first inter-layer dielectric layer 1401, anda wire trace 1403, the second inter-layer dielectric layer 1402, the capfilm layer 1404, and the via fill material 1408. A third inter-layerdielectric layer 1510 is deposited onto the cap film layer 1404. Asecond cap film layer 1512 is deposited onto the third inter-layerdielectric layer 1510. A trench 1514 is defined within the cap filmlayer 1512 and the third inter-layer dielectric layer 1510, for exampleby performing a trench photo-etch and cleaning process. A magnetictunnel junction (MTJ) cell 1516 is deposited within the trench 1514. TheMTJ cell 1516 includes a bottom electrode 1518 that is coupled to thebottom via fill material 1408, an MTJ stack 1520 coupled to the bottomelectrode 1518, and a top electrode 1522 coupled to the MTJ stack 1520.A photo-resist layer 1524 is patterned on the top electrode 1522. Areverse photo-etching process is applied to the photo resist layer 1524,the top electrode 1522, the MTJ stack 1520, and the bottom electrode1518 to remove excess material that is not within the trench 1514.

In this particular example, the trench 1514 is defined to have a trenchdepth (d). The thickness of the bottom electrode 1518 defined a relativeMTJ cell depth (c). In a particular example, the MTJ cell depth (c) isapproximately equal to the trench depth (d) minus the thickness of thebottom electrode 1518.

In general, by fabricating the MTJ cell 1516 within the trench 1514, thedimensions of the trench 1514 define the dimensions of the MTJ cell1516. Further, since the trench 1514 defines the dimensions of the MTJcell 1516, the MTJ cell 1516 can be formed without performing a criticaland expensive photo-etch process on the MTJ cell 1516, thereby reducingoxidation, corner rounding and other erosion-related issues with respectto the MTJ cell 1516.

FIG. 16 is a cross-sectional view 1600 of the circuit substrate 1400 ofFIG. 15 after reverse photo resist strip and MTJ CMP processing to stopat the cap film layer. The circuit substrate 1400 includes the firstinter-layer dielectric layer 1401, the wire trace 1403, the secondinter-layer dielectric layer 1402, and the first cap layer 1404. Theview 1600 includes the second inter-layer dielectric layer 1510, thesecond cap layer 1512 and the MTJ structure 1516. The MTJ structure 1516has an MTJ cell depth (d) and is formed within a trench 1514 having atrench depth (d). The MTJ structure 1516 includes a bottom electrode1518 that is coupled to a via fill material 1408, an MTJ stack 1520, anda top electrode 1522. A photo resist strip process is applied, and anMTJ Chemical-Mechanical Planarization (CMP) process is applied to removeportions of the MTJ structure 1516 to produce a substantially planarsurface 1630. The CMP process is stopped at the second cap film layer1512.

FIG. 17 is a cross-sectional view 1700 of the circuit substrate 1400 ofFIG. 16 taken along line 17-17 in FIG. 16, after photo resist is spun onand patterned, and an MTJ sidewall etch is performed. The circuitsubstrate 1400 includes the first inter-layer dielectric layer 1401, thewire trace 1403, the second inter-layer dielectric layer 1402, the firstcap film layer 1404, and a via fill material 1408. The third inter-layerdielectric layer 1510 and the second cap layer 1512 are deposited on thesecond cap layer 1404. A trench 1514 is defined in the second cap layer1512 and the second inter-layer dielectric layer 1510. The bottomelectrode 1518, the MTJ stack 1520, and the top electrode 1522 areformed within the trench 1514. A Chemical-Mechanical Planarization (CMP)process is applied to produce a substantially planar surface 1630. Aphoto resist layer is spun on and a process pattern opening 1752 isdefined using a photo-etch process. The photo-etch process removes asidewall from the MTJ cell 1516, resulting in a substantially u-shapedMTJ cell 1516 (from a top view).

FIG. 18 is a cross-sectional view 1800 of the circuit substrate 1400illustrated in FIG. 17 after deposition of inter-layer dielectricmaterial within the process opening 1752, after performing achemical-mechanical planarization (CMP) process, and after depositing athird capping layer 1744. The circuit substrate 1400 includes the firstinter-layer dielectric layer 1401, the wire trace 1403, the secondinter-layer dielectric layer 1402, the first cap film layer 1404, and avia fill material 1408. The third inter-layer dielectric layer 1510 andthe second cap layer 1512 are deposited on the first cap film layer1404. A trench 1514 is defined in the second cap layer 1512 and thesecond inter-layer dielectric layer 1510. The bottom electrode 1518, theMTJ stack 1520, and the top electrode 1522 are formed within the trench1514. A Chemical-Mechanical Planarization (CMP) process is applied torestore the substantially planar surface 1630. A process opening 1752 isdefined using a photo-etch process. The photo-etch process removessidewall from the MTJ cell 1516, resulting in a substantially u-shapedMTJ cell 1516 (from a top view). The process opening 1752 is filled withan inter-layer dielectric material 1848, a CMP process is performed torestore the substantially planar surface 1630, and the third cap layer1744 is deposited on the substantially planar surface 1630.

FIG. 19 is a cross-sectional view 1900 of the circuit substrate 1400,which may be coupled to other circuitry. The circuit substrate 1400includes the first inter-layer dielectric layer 1401, the wire trace1403, the second inter-layer dielectric layer 1402, the first cap filmlayer 1404, and a via fill material 1408. The third inter-layerdielectric layer 1510 and the second cap layer 1512 are deposited on thefirst cap film layer 1404. A trench 1514 is defined in the second caplayer 1512 and the second inter-layer dielectric layer 1510. The bottomelectrode 151$, the MTJ stack 1520, and the top electrode 1522 areformed within the trench 1514. A Chemical-Mechanical Planarization (CMP)process is applied to restore the substantially planar surface 1630. Athird cap layer 1744 and a fourth inter-layer dielectric layer 1746 aredeposited. A photo-etch process is applied to define a via 1960 throughthe fourth inter-layer dielectric layer 1746 and the third cap layer1744. The via 1960 is filled with conductive material and a viachemical-mechanical planarization process is applied. A metal wire trace1962 is deposited and patterned on the fourth inter-layer dielectriclayer 1746 and a fifth inter-layer dielectric layer 1948 is deposited.If a Damascene process is used, the via and metal wire can be combinedinto trench patterning, copper plating, and copper CMP in the fifthinter-layer dielectric layer 1948 and the fourth inter-layer dielectriclayer 1746. In a particular embodiment, another chemical-mechanicalplanarization process may be performed to planarize the circuit device.At this stage, the wire trace 1403 and the wire trace 1962 may becoupled to other circuitry, and the MTJ cell 1516 may be used to storeone or more data values.

FIG. 20 is a flow diagram of a particular illustrative embodiment of amethod of forming a magnetic tunnel junction (MTJ) cell. At 2002, a capfilm is deposited onto an inter-layer dielectric layer of a substrate.Advancing to 2004, a via is defined using a photo-etch process, aphoto-resist strip process, and a cleaning process. Continuing to 2006,the via or opening is filled with conductive material and a viaChemical-Mechanical Planarization (CMP) process is performed on thesubstrate to remove excess conductive material. Moving to 2008, aninter-layer dielectric layer (IDL) and a cap film layer are deposited.Continuing to 2010, a trench is defined by photo-etching, stripping aphoto resist, and cleaning.

Proceeding to 2012, a bottom electrode is deposited. Continuing to 2014,multiple magnetic tunnel junction (MTJ) film layers are deposited,including magnetic film and tunnel barrier layers, to form a magnetictunnel junction (MTJ) stack. Continuing to 2016, a top electrode isdeposited on the MTJ stack to form an MTJ cell. Advancing to 2018, areverse trench photo-etch process is performed to remove excess materialthat is not directly over the trench. At 2020, photo-resist is strippedand a MTJ Chemical-Mechanical Planarization (CMP) process is performedto remove excess material, stopping at the cap film layer. Proceeding to2022, the MTJ stack is photo-etched to remove one sidewall of the MTJstack. In a particular embodiment, the photo-etching of the MTJ stackdefines a process window or opening. The method advances to 2024.

Turning to FIG. 21, at 2024, the method advances to 2126 and a photoresist is stripped, an inter-layer dielectric layer is deposited, anoxide Chemical-Mechanical Planarization (CMP) process is performed, anda cap film layer is deposited. Moving to 2128, a magnetic anneal processis performed on the MTJ stack to anneal the fixed magnetic layer in ahorizontal X and Y direction (for a shallow trench) or in a horizontalX-direction and a vertical Z-direction (for a deep trench). Proceedingto 2130, an inter-layer dielectric layer and a cap film layer aredeposited. Continuing to 2132, a via is photo-etched and filled and avia Chemical-Mechanical Planarization (CMP) process is performed.Advancing to 2134, a metal wire is defined by depositing a metal layerand photo-etching the layer to form the wire trace or by forming atrench, photo-etching, plating and performing a Chemical-MechanicalPlanarization (CMP) process. If a Damascene process is used, the viaprocessing at 2132 and the metal wire processing at 2134 can be combinedas trench photo/etch defined, photo resist strip, copper plating, andcopper CMP process. The method terminates at 2136.

FIG. 22 is a flow diagram of a second particular embodiment of a methodof forming a magnetic tunnel junction (MTJ) structure. The methodgenerally includes forming a trench in a substrate, depositing a MTJstructure within the trench, and planarizing the MTJ structure withoutperforming a photo-etch process on the MTJ structure. At 2202, a capfilm is deposited onto an inter-layer dielectric layer of a substrate.Advancing to 2204, a via is defined using a photo-etch process, aphoto-resist strip process, and a cleaning process on the cap film andinter-layer dielectric layers. Continuing to 2206, conductive materialis deposited within the via and a Chemical-Mechanical Planarization(CMP) process is performed to planarize the substrate. Moving to 2208, aILD film layer and a cap film layer may be deposited. Continuing to2210, a trench is defined in the substrate. The trench has dimensionsthat determine the MTJ structure without performing a photo-etchingprocess on the MTJ structure.

Proceeding to 2212, after forming a trench in the substrate, a magnetictunnel junction (MTJ) structure is deposited within the trench. The MTJstructure includes a bottom electrode, a fixed layer, a tunnel barrierlayer, a free layer, and a top electrode. The MTJ structure may alsoinclude an anti-ferromagnetic layer between the bottom electrode and thefixed layer. Additional layers may also be applied, e.g., a seed layer,a buffer layer, a spacer layer, or other layers.

Advancing to 2214, a reverse trench photo etching process may be appliedto remove material that is not directly over the trench. Moving to 2216,the MTJ structure is planarized without performing a photo-etch processon the MTJ structure. For example, a critical/expensive photo-etchprocess is not performed on the MTJ structure. Planarizing the MTJstructure may include performing a CMP process to remove excessmaterial. Deposited material may be eliminated from the substrate todefine a substantially planar surface.

Continuing to 2218, a magnetic annealing process may be performed todefine an orientation of a magnetic field carried by the fixed layer.The magnetic annealing process may be a three-dimensional (3D) annealingprocess. All MTJ layers may be annealed via the magnetic annealingprocess, pinning the fixed layer while allowing the free layer to bemodifiable via a write current. The method terminates at 2220.

FIG. 23 is a flow diagram of a third particular embodiment of a methodof forming a magnetic tunnel junction (MTJ) structure. At 2302, a trenchis defined in a substrate. The substrate may include an inter-layerdielectric layer and a cap film layer. Continuing to 2304-2314, a MTJstructure is deposited within the trench. Depositing the MTJ structuremay include: depositing a bottom electrode within the trench, at 2304;depositing an anti-ferromagnetic layer on the bottom electrode, at 2306;depositing a first magnetic layer on the anti-ferromagnetic layer, at2308; depositing an oxide metal material to form a tunnel barrier, suchas, for example, MgO or AlO, at 2310; depositing a second magnetic layeron the tunnel barrier, at 2312; and depositing a top electrode on thesecond magnetic layer, at 2314.

Proceeding to 2316, excess material that is not directly over the trenchis removed using a low resolution photo etch process. Advancing to 2318,the MTJ structure and the substrate are planarized. Planarizing the MTJstructure and the substrate may include performing a Chemical-MechanicalPlanarization (CMP) process to remove excess material from the MTJstructure and stopping at the cap film layer. A CMP process may beperformed without performing a photo-etching process on the MTJstructure. For example, a critical/expensive photo-etch may not beperformed on the MTJ structure.

Continuing to 2320, a magnetic annealing process is performed on aselected layer to fix an orientation of a magnetic field, the selectedlayer including a fixed layer. The magnetic annealing process may be athree-dimensional (3D) annealing process. Multiple MTJ layers may beannealed via the magnetic annealing process, pinning the fixed layerwhile allowing the free layer to be modifiable via a write current.Moving to 2322, at least two electrical connections to the MTJ structureare formed. The method terminates at 2324.

FIG. 24 is a flow diagram of a fourth particular embodiment of a methodof forming a magnetic tunnel junction (MTJ) structure. At 2402, a trenchis defined in a substrate, the substrate including a semiconductormaterial having an inter-layer dielectric layer and a cap film layer,where the trench extends through the cap film layer and into theinter-layer dielectric layer. The trench may define a shape of the MTJstructure. The trench may have a substantially elliptical shape, asubstantially rectangular shape, or an alternative shape. Continuing to2404, a bottom electrode is deposited within the trench. Moving to 2406,an MTJ structure is deposited on the bottom electrode, the MTJ structureincluding a first ferromagnetic layer, a tunnel barrier layer, and asecond ferromagnetic layer. The MTJ structure may also include otherlayers, such as an anti-ferromagnetic layer between the bottom electrodeand the first ferromagnetic layer. Proceeding to 2408, a top electrodeis deposited on the MTJ structure.

Continuing to 2410, a reverse trench photo-etching process and aplanarization process are performed on the MTJ structure and thesubstrate to produce a substantially planar surface. Performing theplanarization process may include performing a Chemical-MechanicalPlanarization (CMP) process on the MTJ structure and the substrate. TheMTJ structure may thus be formed without performing a photo-etch processon the MTJ structure that may be critical or expensive. The method ternmates at 2412.

FIG. 25 is a block diagram of a representative wireless communicationsdevice 2500 including a memory device having a plurality of MTJ cells.The communications device 2500 includes a memory array of MTJ cells 2532and a magneto-resistive random access memory (MRAM) including an arrayof MTJ cells 2566, which are coupled to a processor, such as a digitalsignal processor (DSP) 2510. The communications device 2500 alsoincludes a cache memory device of MTJ cells 2564 that is coupled to theDSP 2510. The cache memory device of MTJ cells 2564, the memory array ofMTJ cells 2532 and the MRAM device including multiple MTJ cells 2566 mayinclude MTJ cells formed according to a process, as described withrespect to FIGS. 3-24.

FIG. 25 also shows a display controller 2526 that is coupled to thedigital signal processor 2510 and to a display 2528. A coder/decoder(CODEC) 2534 can also be coupled to the digital signal processor 2510. Aspeaker 2536 and a microphone can be coupled to the CODEC 2534.

FIG. 25 also indicates that a wireless controller 2540 can be coupled tothe digital signal processor 2510 and to a wireless antenna 2542. In aparticular embodiment, an input device 2530 and a power supply 2544 arecoupled to the on-chip system 2522. Moreover, in a particularembodiment, as illustrated in FIG. 25, the display 2528, the inputdevice 2530, the speaker 2536, the microphone 2538, the wireless antenna2542, and the power supply 2544 are external to the on-chip system 2522.However, each can be coupled to a component of the on-chip system 2522,such as an interface or a controller.

Those of skill would further appreciate that the various illustrativelogical blocks, configurations, modules, circuits, and algorithm stepsdescribed in connection with the embodiments disclosed herein may beimplemented as electronic hardware, computer software, or combinationsof both. To clearly illustrate this interchangeability of hardware andsoftware, various illustrative components, blocks, configurations,modules, circuits, and steps have been described above generally interms of their functionality. Whether such functionality is implementedas hardware or software depends upon the particular application anddesign constraints imposed on the overall system. Skilled artisans mayimplement the described functionality in varying ways for eachparticular application, but such implementation decisions should not beinterpreted as causing a departure from the scope of the presentdisclosure.

The previous description of the disclosed embodiments is provided toenable any person skilled in the art to make or use the disclosedembodiments. Various modifications to these embodiments will be readilyapparent to those skilled in the art, and the generic principles definedherein may be applied to other embodiments without departing from thespirit or scope of the disclosure. Thus, the present disclosure is notintended to be limited to the embodiments shown herein but is to beaccorded the widest scope possible consistent with the principles andnovel features as defined by the following claims.

Those of skill would further appreciate that the various illustrativelogical blocks, configurations, modules, circuits, and algorithm stepsdescribed in connection with the embodiments disclosed herein may beimplemented as electronic hardware, computer software, or combinationsof both. To clearly illustrate this interchangeability of hardware andsoftware, various illustrative components, blocks, configurations,modules, circuits, and steps have been described above generally interms of their functionality. Whether such functionality is implementedas hardware or software depends upon the particular application anddesign constraints imposed on the overall system. Skilled artisans mayimplement the described functionality in varying ways for eachparticular application, but such implementation decisions should not beinterpreted as causing a departure from the scope of the presentdisclosure.

The steps of a method or algorithm described in connection with theembodiments disclosed herein may be embodied directly in hardware, in asoftware module executed by a processor, or in a combination of the two.A software module may reside in RAM memory, flash memory, ROM memory,PROM memory, EPROM memory, EEPROM memory, registers, hard disk, aremovable disk, a CD-ROM, or any other form of storage medium known inthe art. An exemplary storage medium is coupled to the processor suchthat the processor can read information from, and write information tothe storage medium. In the alternative, the storage medium may beintegral to the processor. The processor and the storage medium mayreside in an ASIC. The ASIC may reside in a computing device or a userterminal. In the alternative, the processor and the storage medium mayreside as discrete components in a computing device or user terminal.

The previous description of the disclosed embodiments is provided toenable any person skilled in the art to make or use the disclosedembodiments. Various modifications to these embodiments will be readilyapparent to those skilled in the art, and the generic principles definedherein may be applied to other embodiments without departing from thespirit or scope of the disclosure. Thus, the present disclosure is notintended to be limited to the embodiments shown herein but is to beaccorded the widest scope possible consistent with the principles andnovel features as defined by the following claims.

What is claimed is:
 1. A magnetic tunnel junction (MTJ) device formed bya process comprising: forming a trench in a substrate; depositing an MTJstructure within the trench, the MTJ structure including a bottomelectrode, a fixed layer, a tunnel barrier layer, a free layer, and atop electrode; applying a reverse photo etching process to removematerial that is not directly over the trench; and planarizing the MTJstructure without performing a photo-etch process on the MTJ structure.2. The MTJ device of claim 1, wherein the substrate comprises aninter-layer dielectric layer and a cap film layer.
 3. The MTJ device ofclaim 1, wherein forming the MTJ device further comprises performing amagnetic annealing process to define an orientation of a magnetic fieldcarried by the fixed layer.
 4. The MTJ device of claim 1, wherein thetrench has a substantially rectangular shape.
 5. The MTJ device of claim1, wherein planarizing the MTJ structure comprises performing achemical-mechanical planarization process on the MTJ structure.
 6. Anapparatus for forming a magnetic tunnel junction (MTJ), the apparatuscomprising: means for forming a trench in a substrate; means fordepositing an MTJ structure within the trench, the MTJ structureincluding a bottom electrode, a fixed layer, a tunnel barrier layer, afree layer, and a top electrode; means for removing material that is notdirectly over the trench; and means for planarizing the MTJ structurewithout performing a photo-etch on the MTJ structure.
 7. The apparatusof claim 6, wherein the means for removing includes means for applying areverse photo etching process.
 8. The apparatus of claim 6, furthercomprising means for performing a magnetic annealing process to definean orientation of a magnetic field carded by the fixed layer.
 9. Theapparatus of claim 6, further comprising means for depositing a cap filmlayer onto an inter-layer dielectric layer of the substrate.
 10. Theapparatus of claim 9, further comprising means for forming a via using aphoto-etch process, a photo-resist strip process, and a cleaning processon the cap film layer and on the inter-layer dielectric layer.
 11. Theapparatus of claim 10, further comprising: means for depositingconductive material within the via; and means for planarizing thesubstrate.
 12. A method comprising: forming a trench in a substrate;depositing an MTJ structure within the trench, the MTJ structureincluding a bottom electrode, a fixed layer, a tunnel barrier layer, afree layer, and a top electrode; removing material that is not directlyover the trench; and planarizing the MTJ structure without performing aphoto-etch on the MTJ structure.
 13. The method of claim 12, whereinremoving the material includes applying a reverse photo etching process.14. The method of claim 12, further comprising performing a magneticannealing process to define an orientation of a magnetic field carriedby the fixed layer.
 15. The method of claim 12, further comprisingdepositing a cap film layer onto an inter-layer dielectric layer of thesubstrate.
 16. The method of claim 15, further comprising forming a viausing a photo-etch process, a photo-resist strip process, and a cleaningprocess on the cap film layer and on the inter-layer dielectric layer.17. The method of claim 16, further comprising: depositing conductivematerial within the via; and planarizing the substrate.
 18. The methodof claim 17, wherein planarizing the substrate comprises performing achemical-mechanical planarization process on the substrate.
 19. Themethod of claim 12, wherein the trench has a substantially rectangularshape.
 20. The method of claim 12, wherein planarizing the MTJ structurecomprises performing a chemical-mechanical planarization process on theMTJ structure.